Caloric restriction (CR: reducing caloric intake 30-40 percent below ad libitum levels) remains the only intervention that reproducibly extends lifespan, reduces the incidence and delays the onset of age-related disease, enhances stress protection, and attenuates functional decline in mammals. The NIA longitudinal study of CR and aging in rhesus monkeys finished its 20th year. Monkeys continue to be monitored regularly.[unreadable] [unreadable] Eye exams and fundus photos were completed on all the monkeys. The monkeys showed a high prevalence of drusenoid maculopathy which was age-related and similarly occurs in humans. Tests of locomotor behavior have continued and show an age-related decline in home cage activity. CR monkeys tend to be more active than controls during the day but less active at night. Complex tasks of learning and memory using custom-made portable touch-screen panels are currently underway. Motor performance was assessed using an automated monkey Movement Assessment Panel (mMAP) that has reproducibly and reliably measured reaction time, coarse-motor, and fine-motor movement in rhesus monkeys and humans. In our study, an age-related decline in fine motor performance has been observed that was partially ameliorated in the CR monkeys. A study of ligature-induced inflammation in the oral cavity was completed in a subset of monkeys. Local and systemic measures of immune function were evaluated for 90 days and on several measures CR had beneficial effects. We continue to monitor morbidity and mortality but the number of deaths and diagnosed diseases remains too low for conclusive statistical analyses.